Question: What is the standard deviation of the uncertainty of the half-life of a neutron?
Paraphrase: Although no certain answer exists, what is the standard deviation of a neutron's half-life?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q2348 p:P2114 ?s . ?s ps:P2114 ?obj . ?s pq:P2571 wd:Q159375 }